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Altered Complexity of Spontaneous Brain Activity in Schizophrenia and Bipolar Disorder Patients
Nan Zhang1, Yan Niu1, Jie Sun1
1College of Information and Computer, Taiyuan University of Technology, Taiyuan, Shanxi, China.
Background:
Schizophrenia (SC) and bipolar disorder (BP) share elements of symptoms and the underlying neural mechanisms for both remain unclear. Recently, the complexity of spontaneous functional MRI (fMRI) signals in brain activity has been investigated in SC and BP using multiscale sample entropy (MSE) with inconsistent results.
Purpose:
To perform MSE analysis across five time scales to assess differences in resting-state fMRI signal complexity in SC, BP, and normal controls (NC).
Study Type:
Retrospective.
Population:
Fifty SC, 49 BP, and 49 NC.
Field Strength/Sequence:
A 3 T, T2* weighted echo planar imaging (EPI) sequence.
Assessment:
The mean MSEs of all gray matter (GM) and of 12 regions of interest (ROIs) were extracted using masks across the five scales. The regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) in these ROIs were also determined and the relationship between the three measures was investigated. The correlations between cognitive assessment scores and MSE values were also explored.
Statistical Tests:
Bonferroni correction, One-way ANOVA, Spearman rank correlation coefficient (r), Gaussian random field (GRF) correction.
Results:
There were decreased GM MSE values in the patient groups (F = 9.629, P < 0.05). SC and BP patients demonstrated lower complexity than NCs in the calcarine fissure, precuneus, inferior occipital gyrus, lingual gyrus and cerebellum, and higher complexity in the median cingulate, thalamus, hippocampus, middle temporal gyrus and middle frontal gyrus. There were significant differences between SC and BP patients in the precuneus (F = 4.890, P < 0.05) and inferior occipital gyrus (F = 5.820, P < 0.05). Calcarine fissure, cingulate, temporal gyrus, occipital gyrus, hippocampus, precuneus, frontal gyrus, and lingual gyrus MSE values were significantly correlated with both ReHo (r > 0.282, P < 0.05) and ALFF (r > 0.278, P < 0.05). Furthermore, median temporal MSE (r = -0.321, P < 0.05) on scale 3 and (r = -0.307, P < 0.05) on scale 4 and median cingulate MSE (r = -0.337, P < 0.05) on scale 5 was significantly negatively correlated with cognitive assessment scores.
Data Conclusion:
These data highlight different patterns of brain signal intensity complexity in SC and BP.
Level Of Evidence:
1 TECHNICAL EFFICACY: Stage 1.
Insights
Schizophrenia (SC) and bipolar disorder (BP) patients exhibit altered brain signal complexity compared to controls. These findings reveal distinct patterns in SC and BP, impacting cognitive function.
Area of Science:
- Neuroscience
- Psychiatry
- Medical Imaging
Background:
- Schizophrenia (SC) and bipolar disorder (BP) share overlapping symptoms, but their underlying neural mechanisms remain unclear.
- Previous studies using multiscale sample entropy (MSE) on functional MRI (fMRI) signals in SC and BP have yielded inconsistent results regarding brain activity complexity.
Purpose of the Study:
- To analyze resting-state fMRI signal complexity differences in SC, BP, and normal controls (NC) using MSE across five time scales.
- To investigate the relationship between MSE, regional homogeneity (ReHo), and amplitude of low-frequency fluctuation (ALFF) in specific brain regions.
- To explore correlations between MSE values and cognitive assessment scores in patient groups.
Main Methods:
- Retrospective analysis of fMRI data from 50 SC, 49 BP, and 49 NC participants.
- Multiscale sample entropy (MSE) analysis applied to gray matter and 12 regions of interest (ROIs) using a 3T, T2* weighted EPI sequence.
- Regional homogeneity (ReHo) and amplitude of low-frequency fluctuation (ALFF) were calculated; statistical analyses included Bonferroni correction, ANOVA, and Spearman correlation.
Main Results:
- Decreased gray matter MSE values were observed in both SC and BP groups compared to NC.
- SC and BP patients showed reduced complexity in areas like the calcarine fissure, precuneus, and occipital gyrus, but increased complexity in regions such as the thalamus and hippocampus.
- Significant differences in complexity between SC and BP were found in the precuneus and inferior occipital gyrus. MSE values correlated significantly with ReHo and ALFF, and negatively with cognitive scores in specific regions.
Conclusions:
- The study reveals distinct patterns of brain signal complexity in schizophrenia and bipolar disorder.
- These complexity differences are associated with regional brain activity measures (ReHo, ALFF) and cognitive function.
- The findings contribute to understanding the neural underpinnings of SC and BP, highlighting specific regional alterations.
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